I started on 35 too...got tired of the small negs and the nasty grain. Then, came the C330, then the RB... I shot all over the country with my RB, I shot weddings, portraits, hiked all over the place with her...
One thing larger formats teach you is how to nail an exposure the FIRST time around
I loved the square, then adjusted to the 6x7's "perfect" proportions (perfect for matching an 8x10 piece of paper...). I tried 645 for about 2 weeks, but got tired of the rectangular shots. And, promptly got rid of it.
Then, I had a Pentax 67II for 4 days before I threw the camera about 20 feet on asphalt (I hated that thing so much I actually got more satisfaction out of hearing the "crrrrasshhhhh....clank, clank, thunk" than I would of selling it!) And, back to the RB...then, I got an RZ...
Then, I wanted more contrast that the Mamiya glass (it's actually quite good glass, but then I saw Zeiss glass...) and I wanted back into the square.
Then, I got to shoot a Crown Graphic...then an 8x10 Wisner...then a Contax 645.
Then, came the pinhole. Then, the Sinar F1. But, I hated the single/double shot method and the carrying around tons of gear needed with LF.
So, I went back to the RB/RZ.
Then, I bought a C-41 processor, ... and a RA-4 roller-transport processor, and I wanted more color saturation...so, I started searching again (and drooling over Zeiss glass)!
Finally, I'm back to MF (and looking to stay here for a while). I got a full Hasselblad system, with a ton of lenses, backs, etc.
I still love LF for product/still life/commercial work. And, for portraits, I love the RB, the negs are great for printing. The rest of the time, I use my beloved Hassy (named Holly...one of these days I'll publish a coffee-table book named "around the world, just me and Holly") Ok, ok...I know...
I think that MF is the best "mean" between LF quality and SF convenience. I haven't used a SF camera in over 6 years now. And I don't think I ever will (well, the Contax TVSIII is looking kinda cool for a "keep on you for quick snaps" type of camera...)
One of these days, though, I will take a shot or two off the Polaroid 20x24 (when I can justify the expense of renting the thing...geez) The funny thing is that I really haven't loss any money moving between all these systems (it's all about who you know (and where they work) )
Yup, they're all tools. And, they all have their "optimal" uses, SF for speed and machine-gun frame rates, LF for quality and back-aches, MF for decent speed & portability with nice quality. Even digital has it's place too (not for me, but there are it's uses...)
I think the 6x9 cameras are neat, but printing them can be a pain at times. The RB isn't as heavy of a camera as people make it out to be. There are so many things that the RB/RZ series has which makes it nice, like bellow focusing (precise and no need for extension tubes), rotating back (no need to flip the camera for horiz vs vert shots), cheap (especially right now with all the studios closing or changing to digital), and the big viewfinder is really nice to work with!
A Fuji 690 is a neat RF camera. I've been thinking about one for vacation/travelling. Except for the 8 shots, though...
I'd say that you go to your local camera shop, but a couple of rolls of film, and ask them to let you shoot around the store with different formats. Then, get the shots developed and see what format you seem to fit "into" the most.